Pick any two UK PAYE tax codes and we will line up the allowance, emergency status, region and approximate annual tax on a £30,000 salary so you can see exactly how they differ.
Last updated 2026-04-12
| Attribute | K400 | 1257Y |
|---|---|---|
| Category | KCode | Standard |
| Region | rUK | rUK |
| Allowance | £-4,000 | £12,570 |
| Emergency / non-cumulative | No | No |
| Approx. annual tax on £30k | £6,800 | £3,486 |
| In one sentence | Adds £4,000 to your taxable pay because untaxed income exceeds your allowance. | You were born before 6 April 1938 - historical age-related allowance marker. |
Bottom line on £30k
On a £30,000 salary, K400 deducts roughly £6,800 in income tax per year vs £3,486 for 1257Y. That is a difference of £3,314 per year - K400 is more expensive.
Hand-picked side-by-sides that answer the most-searched UK tax-code questions.
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